The present invention relates to application specific integrated circuits (ASICs), and more particularly, to ASICs for controlling operations of various appliances such as printers.
Many electronic appliances include a processor, a control processor, to control operations of various components of the appliance. Some appliances include a second processor, a data processor, to process relatively large amounts of relatively complex data received by the appliance, generated by the appliance, or both. Further, these processors are often attached to their own printed circuit boards (PCBs). For example, current generation printers typically have this configuration.
FIG. 1A is a simplified schematic illustration of an appliance 10 (for example, a laser printer 10) having a prior art configuration. FIG. 1B is a more detailed schematic illustration of portions of the appliance 10. Referring to FIGS. 1A and 1B, the printer 10 receives complex data 22 from a host computer 20. The data 22 is analyzed and formatted by a data processor 32 on a formatter board 30. The formatted data is communicated to a control processor 42 on an engine controller board 40. The two processors 32 and 42 typically communicate via a serial interface 41.
The data processor 32 is typically a high performance ASIC (application specific integrated circuit) 32 having a number of portions integrated within the ASIC 32. For example, the ASIC 32 includes a processing core 36 and its own internal memory 34 such as DRAM (dynamic random access memory) 34.
Further, the ASIC 32 may include other integrated portions 38 not illustrated in detail. The ASIC 32 operates at a relatively high speed, for example, 100 MHz, to perform complex tasks such as formatting the complex data 22 in preparation for printing by the printer 10. The formatted data is sent to the control processor 42 for printing.
The ASIC 32 is connected to an external memory 39 such as flash memory 39 containing instructions and various parameters used for the operations of the ASIC 32. Flash memory technology is known in the art as non-volatile memory that can be erased, reprogrammed, or updated. By updating the flash memory 39, the operations of the data processor 32 can be updated to accommodate updates or changes in technology.
The control processor 42 is typically a low performance microcontroller (compared to the data processor 32). The control processor 42 includes ROM (read only memory) 43 to permanently store instructions for its processor 46 and may include additional memory elements such as SRAM 44 (static random access memory) for its operation. The control processor 42 receives page formatting information
The control processor 42 receives page formatting information from the data processor 32 and controls various electro-mechanical components (represented here as a box 50) to generate a printed page in accordance with the formatted data received from the data processor 32. The control processor 42 includes analog-to-digital converters (ADC) and digital-to-analog converters (DAC), collectively illustrated as ADAC 48. The ADAC 48 are connected to, communicate with, and control analog components 49 on the engine controller board 40. The analog components 49 are connected to, communicate with, and control the electro-mechanical components 50 of the printer 10. The electro-mechanical components 50 include, for example only, fuser, stepper motor, laser scanner, voltage supply, printer engine, page timer, drum, and paper sensors.
The current design suffers from a number of disadvantages. For example, two printed circuit boards 30 and 40 introduce complexity and require significant area and space within the printer 10. The two processors 32 and 42 often require different voltage levels requiring separate power supply circuitry for each of the processors 32 and 42. The instructions for the control processor 42 are embedded in the read only memory (ROM) 43. Accordingly, it cannot be updated after the initial programming. Since the ROM 43 cannot be updated after the initial programming, printer specific control processors 42 are programmed and stocked for each type and model of printer. The control processors 42 cannot be shared between differing models of the printers. In fact, even for the same model printers, differently programmed control processors 42 are stocked to accommodate printers shipped to differing areas. For example, different parameter settings, for example temperature settings for fusers, are needed for printers shipped to tropical regions compared to printers shipped to arctic regions.
Accordingly, there remains a need for a method and apparatus to eliminate or alleviate these disadvantages of the current appliances.